Severely limiting it by killing it. Also most beneficials make a symbiotic relationship with the roots. This can only happen if there is something for the bennies to eat. Organic material. Not synthetic nutrients.
Soil is a vague term. Not all soils are alike. So to say every soil mix reacts the same is dumb. The only way soil can buffer pH is by adding something to buffer it. Gypsum, dolomite lime, pH up and down, pine needles and what not. also we are talking about growing in pots indoors. Not much Mother Nature to get involved indoors. Stop coming off like you know everything. It's getting old.
Frequently we see statements in the lay literature about chemical fertilizers killing soil microbes or, worse yet, statements indicating these management inputs "sterilize" the soil.
Statements such as these should be viewed with much skepticism! Remember that as we learned in FAQ #1, the soil can contain tons of microbes. Short of incineration its hard to imagine a stress in a soil that would lead to complete extermination of the microbial populations. It is true that some inputs, e.g., anhydrous ammonia, cause reductions in microbial numbers in the immediate vicinity of the application. After all, ammonia is a toxic gas. However, it quickly equilibrates with the soil solution in the form of ammonium ions and the toxicity subsides. Certain pesticides have been shown to cause similar transient reductions in selected microbial population. But remember, in some cases the microbes simply view these chemicals as food and degrade them fairly quickly.
Organic fertilizers circumvent the criticisms leveled at "synthetic" fertilizers but it should not be forgotten that plants take up nitrogen in the form of ammonium (NH4+) or nitrate (NO3-) ions regardless of whether it was mineralized from an organic source or applied as in inorganic fertilizer like ammonium nitrate. An advantage of using organics, where practical, is that nutrients are liberated slowly as the microbes mineralize the organic materials. Thus there is low risk for fertilizer burn on plants and less risk for environmental problems due to runoff and leaching. Another potentially negative effect of long-term use of ammonia-based fertilizers is soil acidification due to ammonia oxidation by the nitrifying bacteria. Soil pH can drop below 5.0 after prolonged use of ammonia-based fertilizers and this can cause marked reductions in populations of bacteria and actinomycetes and simultaneous increases in the relative abundance of fungi. Such changes might favor the development of certain fungal plant pathogens. On the other hand, the potato scab disease is reduced by the low pH because the actinomycete which causes it is eliminated. These changes are easily reversed with applications of lime to the soil.
Thus we see qualitative changes in the soil populations due to some management inputs but this is a long way from "sterilizing" or "killing" the soil.
With the advent of high-sand golf greens questions have arisen about the need for applying microbes during green construction and thereafter. Sand because of its lack of organic matter supports little microbial growth. However, when mixed with peats, composted rice hulls or other organic amendments it gains the microbial populations associated with those materials. Turfgrasses established from vegetative sprigs also bring their root-associated microbes with them! Once the turfgrass begins growing in the rooting medium of the green, microbes already present will colonize roots and the mechanics of soil organic matter formation will commence. A reasonable practice would be to add a small amount of normal pathogen-free soil to the greens mix as an inoculum. Thus far, there is little scientific evidence indicating the need to inoculate golf greens with selected microorganisms. The newly constructed green does afford us the possibility of customizing the soil population to some extent. Once we know what we want in these mixes it may be easier to add them "up front" than to add them into an established population already adapted to the prevailing conditions of a particular soil. As our knowledge of soil microbial biodiversity and the factors that control it increases we may find ways of tailoring microbial populations in given environments. At this point, we are limited in what we can do to this effect.
source,
http://organiclifestyles.tamu.edu/soil/microbeindex.html